Oscillators – Gibilisco MCQs in Electronics

This is the Multiple Choice Questions (MCQs) in Chapter 25: Oscillators from the book Teach Yourself Electricity and Electronics, 5th edition by Stan Gibilisco. If you are looking for a reviewer in Electronics Engineering this will definitely help you before taking the Board Exam.

Start Practice Exam Test Questions

1. Negative feedback in an amplifier:

A. Causes oscillation.

B. Increases sensitivity.

C. Reduces the gain.

D. Is used in an Armstrong oscillator.

2. Oscillation requires:

A. A common-drain or common-collector circuit.

B. A stage with gain.

C. A tapped coil.

D. Negative feedback.

3. A Colpitts oscillator can be recognized by:

A. A split capacitance in the tuned circuit.

B. A tapped coil in the tuned circuit.

C. A transformer for the feedback.

D. A common-base or common-gate arrangement.

4. In an oscillator circuit, the feedback should be:

A. As great as possible.

B. Kept to a minimum.

C. Just enough to sustain oscillation.

D. Done through a transformer whose wires can be switched easily.

5. A tapped coil is used in a(n):

A. Hartley oscillator.

B. Colpitts oscillator.

C. Armstrong oscillator.

D. Clapp oscillator.

6. An RF choke:

A. Passes RF but not dc.

B. Passes both RF and dc.

C. Passes dc but not RF.

D. Blocks both dc and RF.

7. Ferromagnetic coil cores are not generally good for use in RF oscillators because:

A. The inductances are too large.

B. It’s hard to vary the inductance of such a coil.

C. Such coils are too bulky.

D. Air-core coils have better thermal stability.

8. An oscillator might fail to start for any of the following reasons except:

A. Low-power-supply voltage.

B. Low stage gain.

C. In-phase feedback.

D. Very low output impedance.

9. An advantage of a crystal-controlled oscillator over a VFO is:

A. Single-frequency operation.

B. Ease of frequency adjustment.

C. High output power.

D. Low drift.

10. The frequency at which a crystal oscillator functions is determined mainly by:

A. The values of the inductor and capacitor.

B. The thickness of the crystal.

C. The amount of capacitance across the crystal.

D. The power-supply voltage.

11. The different sounds of musical instruments are primarily the result of:

A. Differences in the waveshape.

B. Differences in frequency.

C. Differences in amplitude.

D. Differences in phase.

12. A radio-frequency oscillator usually:

A. Has an irregular waveshape.

B. Has most or all of its energy at a single frequency.

C. Produces a sound that depends on its waveform.

D. Uses RC tuning.

13. A varactor diode:

A. Is mechanically flexible.

B. Has high power output.

C. Can produce different waveforms.

D. Is good for use in frequency synthesizers.

14. A frequency synthesizer has:

A. High power output.

B. High drift rate.

C. Exceptional stability.

D. Adjustable waveshape.

15. A ferromagnetic-core coil is preferred for use in the tuned circuit of an RF oscillator:

A. That must have the best possible stability.

B. That must have high power output.

C. That must work at microwave frequencies.

D. No! Air-core coils work better in RF oscillators.

16. If the load impedance for an oscillator is too high:

A. The frequency might drift.

B. The power output might be reduced.

C. The oscillator might fail to start.

D. It’s not a cause for worry; it can’t be too high.

17. The bipolar transistors or JFETs in a multivibrator are usually connected in: